A need exists in the mail sorting industry for a way to accurately measure the mass or weight of a postal item, such as a letter, in order to validate postage paid. One method of accomplishing this is with the use of a high accuracy scale. Such scales, however, require the slowing down or complete stopping of the sorting process. In addition, these high accuracy scales are very expensive.
Another method determines force and acceleration to compute mass by applying a known torque and monitoring velocity at start and end times of a letter being accelerated. Such method has not been found to provide a desired degree of accuracy and repeatability.
An improved method for determining the mass or weight of a letter without slowing or stopping the sorting process is desired.